It is useful in the field of electronic circuits to provide a constant and stable reference voltage. For example reference voltages of around 1.25V are common as this is close to the theoretical bandgap of silicon at 0 K.
An example prior art system that provides a reference voltage is a “bandgap reference voltage circuit”. Various methods have been proposed including those by Widlar, R., “New Developments in IC Voltage Regulators,” IEEE Journal of Solid-State Circuits, Vol. SC-6, pp. 2-7, February 1971; K. Kuijk, “A Precision Reference Voltage Source,” IEEE Journal of Solid-State Circuits, Vol. SC-8, pp. 222-226, June 1973; and H. Banba, et. al., “A CMOS Bandgap Reference Circuit with sub-1-V Operation,” IEEE Journal of Solid-State Circuits, Vol. 34, pp. 670-674, May 1999.